Brain Jazz 2 is a performance/installation for the soloist, programmer, two assistants and the MAX/MSP based brain-wave biofeedback system. During the interactive performance the system measures performer’s electroencephalogram (EEG), which is a complex signal and an important brain state indicator. It is registered by means of electrodes placed on the scalp. The system is analyzing and interpreting incoming data into the process of generation and development of the flexible musical structure.
The spectrum of the raw EEG signal is transposed up by means of the phase vocoder to fit the audible range.
While the process of generation of sound texture depends on the slow changing data and an extra real time sound processing, based on the relative values of the mean spectral power of alpha, beta, theta and delta EEG frequency bands, all fast processes, related to rhythm and fermatas as well as a macro-segmentation of the audio stream (a counterpart of the musical phrase) depend on mimics of the face of the performer, gaining a kind of ‘semantic feedback’ with the audience.